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  1. hevans1944

    Help a blind man in electricity

    I am squinting very hard, but I don't see any color in the drawing @Tightbudget submitted. Where is the red wire?
  2. hevans1944

    110 VAC timer

    It's called an "elapsed time meter" and most of them are electro-mechanical, consisting of a synchronous motor and gear train driving an odometer type display with 0.1 hour (six minutes) resolution. Your can try searching here, but most of the ones I found do not display down to seconds, much...
  3. hevans1944

    Current limiting using an Arduino microcontroller

    Wow! Serendipity strikes again. I spent years standing too close to the stage listening to rock music, and years after that blasting it into headphones. As a result I have suffered some hearing loss in both ears. Not enough to make me plunk down big bucks for hearing aids, but enough to almost...
  4. hevans1944

    Current limiting using an Arduino microcontroller

    I said nothing about the speed of the LT3092. This is a strictly analog constant-current source operating from a fixed DC supply. Speed of response is usually not an issue. It was my impression that you were unsatisfied with its minimum current output of 0.5 mA and wanted to use PWM with a...
  5. hevans1944

    Anyone near Indiana?

    Yeah, just a phase. Should be all gone tomorrow here in Dayton, but more is expected until the vernal equinox arrives on Sunday, March 20 at 12:30 AM. Maybe also some more solid DHMO after that. There was solid DHMO falling from the sky when my oldest daughter was born on April 9, 1973.
  6. hevans1944

    Precision Rectifier

    I doubt the 1N4148 diodes are a problem. They do not have to be matched for the circuit to work properly. Fifty hertz (or even 60 Hz) is a low enough frequency that slew rate in the op-amps should not be a problem. Since you get a clean sine wave at the output of U1A, there is no problem with...
  7. hevans1944

    Anyone near Indiana?

    No. Beach sand is mainly SiO2 (silicon dioxide). What you have there is H2O (dihydrogen monoxide or DHMO), an extremely dangerous substance that, if inhaled in large quantities, can be fatal. It is also extremely dangerous in the solid form shown in the picture, causing an immediate reduction in...
  8. hevans1944

    Current limiting using an Arduino microcontroller

    @Michael Matrix please revisit the circuit that @Harald Kapp referenced. It uses a voltage-output digital-to-analog converter (DAC) to control a LT3092 three-terminal regulator connected in constant-current mode with a 0 to 1 V control signal from the DAC. One electrode (anode) of the TDCS...
  9. hevans1944

    Precision Rectifier

    Looks like something is clipping (flat top) and slew-rate limiting (kink in the waveform) your signal. Why is the input attenuated with a 10 Meg-ohm/150 kΩ divider? Is there a clean sine wave on the top end of the 10 Meg-ohm resistor? Is there a cleanly reduced version of the sine wave on the...
  10. hevans1944

    DC Power Supply Noise?

    Would love to, and may do so another year, but other things prevent it this year. My father passed at age 82. He lived a full and interesting life: Retired after an Air Force career to become a businessman (with his brother-in-law) here in Dayton, and finally another career as an entrepreneur...
  11. hevans1944

    Frequency accuracy

    @Paul Jefferies: And then there is the other method (NOT recommended) that many hams appear to use today: transmit where you will and wait for someone to tell you "You're outta da band, Lid!" Of course you wouldn't hear them because they are transmitting inside the ham band whereas you are...
  12. hevans1944

    Wire size for current?

    Probably too late now, but did anyone think about increasing the DC voltage from the alternator to 24 VDC? Probably not compatible with your other stuff at this point in time... Yes, do as @Tha fios agaibh suggested and put the up-converter close to the source of power but use adequately sized...
  13. hevans1944

    Laser Beam

    Colin, it's a POS laser-pointer diode emitter mounted next to a photo-sensor (both unspecified) with a lens. It is intended to be used as a reflective "trip wire" sensor, reflector also unspecified. That's why the "range" is so short. It would probably work at longer distances if you could...
  14. hevans1944

    Hello Everyone, I am off to a rocky start!

    Yeah, Larry, welcome to Electronics Point. We might rake you over the coals a little bit since you are an old newbie, but you will have fun. Don't worry 2 much bout spullin. And one LOL goes a long way here. I envy you your motorcycle racing. My wife won't let me get on my bike again unless I...
  15. hevans1944

    how can I make my pc to be i/o device for microcontroller by wireless means

    Wireless, huh? Google stuff on Bluetooth. You will need a transceiver at your PC and another one at your microcontroller or sensors and camera. Not for the faint-hearted getting a video signal across a Bluetooth RF link, but probably doable if a low frame-rate and a video buffer is used. Do you...
  16. hevans1944

    Voltage Upper Circuit - Prebuilt solution

    Anything you build that provides 4000 V from an AC mains source can be LETHAL. This is an especially dangerous idea to incorporate into a bug zapper with exposed wires. Clearly, you don't have enough knowledge or experience to "play around" in this area... you don't get DC from a transformer is...
  17. hevans1944

    DC Power Supply Noise?

    I know nothing about tanks, but I appreciate the efforts of you and hundreds (thousands?) of others who help preserve the history of WWII. I was a month short of one year old on VE day, but my father had been a POW in Germany in Stalag Luft 3, having been shot down on May 24, 1944 during a B-17...
  18. hevans1944

    One button power door locks

    @AnalogKid, I LIKE IT! Had forgotten these existed. Much better solution than the two mechanically latched relays. Good job, Kid! You can also interchange the +12 and GND connections if the door lock requires a +12V pulse instead of a ground.
  19. hevans1944

    Does this part exist?

    Sounds like the same action as an old-fashioned ball-point pen: press to extend pen nib, press again to retract it. Inside is a little plastic rotary cam, and a spring. The same action is available in commercial push-button switches. @Minder has recommended one line and brand that may suit your...
  20. hevans1944

    One button power door locks

    @Bluejets Your revised circuit will energize both coils simultaneously until the capacitor charges. Then both coils will de-energize, but the final state depends on which one de-energizes last. Please try again. I am "pretty sure" this has a "simple" solution that does not depend on the...
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